Non-random chromosomal abnormalities have been identified in many hematologic malignancies. Cloning of the breakpoints involved in the abnormalities has led to the identification of the affected genes and the molecular genetic consequences of the rearrangements. Known proto-oncogenes have been found to be deregulated by translocations and new biomedically important genes have been identified at the breakpoints with resultant insights into the mechanisms of normal hematopoiesis as well as leukemogenesis. Solomon, E. et al., Science 254:1153 (1991); Nichols, J. et al. Blood 80:2953 (1992); Rabbits T. H., Cell 67:641 (1991); and Yunis, J. J. et al., Crit. Rev. Oncogen. 4:161 (1993). In leukemias, at least two mechanisms have been identified for the deregulation of cellular proto-oncogenes by chromosome rearrangements. The first is the juxtaposition of a cellular proto-oncogene to the regulatory elements of a tissue specific gene, particularly the immunoglobulin and T cell receptor genes, leading to the inappropriate expression of the oncogene. Leder, P. et al., Science 222:765 (1983); Finger, L. R. et al., Science 234:982 (1986). The second is gene fusion at the junction of a translocation, generating a chimeric mRNA and a protein with transforming properties. Borrow, A. D. et al., Science 249:1577 (1990) and de The, H. et al., Nature 347:558 (1990)
A characteristic chromosome 16 pericentric inversion, inv(16)(p13q22), has been found in almost all patients with abnormal bone marrow eosinophilia (M4Eo), which constitutes about 8% of acute myeloid leukemia (AML) patients. Arthur, D. C. et al., Blood 61:994 (1983); LeBeau, M. M. et al., N. Engl. J. Med. 309:630 (1983); Mitelman, F. et al., Genes Chrom. Cancer 5:57 (1992); Heim, S. et al., Can. Suppl. 70:1701 (1992). Given the absence of other karyotypic abnormalities in many of these patients and the fact that patients treated in several studies had the inversion chromosome disappear upon remission, a pathogenic relationship between inversion 16 and acute myelomonocytic leukemia (AMML) M4Eo has been suggested. Arthur, D. C. et al., Blood 61:994 (1983); LeBeau, M. M. et al., N. Engl. J. Med. 309:630 (1983); Mitelman, F. et al., Genes Chrom. Cancer 5:57 (1992); Heim, S. et al., Can. Suppl. 70:1701 (1992); "Fourth International Workshop on Chromosomes in Leukemia, 1982," Can. Genet. Cytogen. 11:275 (1984); and Bennett, J. M. et al., Ann. Intern. Med. 103:626 (1985).
The breakpoints associated with this chromosome rearrangement had not, however, been previously cloned. Genetic events associated with this chromosomal aberration and their relationship to leukemogenesis, therefore, remained unidentified, although some progress in identifying the molecular events associated with inversion 16 (also referred to as inv(16) herein) was made. For instance, the long arm breakpoint of inv(16) was mapped between two anonymous DNA sequence markers found to be within 450 kb from each other. Callen, D. F. et al., Am. J. Hum. Genet. 51:A57 (1992). By fluorescence in situ hybridization (FISH), the p arm breakpoint was mapped between anonymous cosmids located in band 16p13.13 separated by an unknown distance. Wessels, J. W. et al., Blood 77:1555 (1991) It was also suggested that the breakpoint was within a chromosome 16-specific repeat sequence which might play a role in the origin of chromosome 16 rearrangements in the leukemia. Dauwerse, J. G. et al., Blood 79:1299 (1992) and Stallings, R. L. et al., Genomics 13:332 (1992).
Sensitive molecular analysis has also not been available for diagnosis and monitoring of patients with inv(16) leukemia. Identification of the inversion has generally been performed with karyotyping by G-banding. This procedure however, is not very sensitive due to the poor quality of clinical samples and the fact that chromosome 16 is a short chromosome with few identifiable banding landmarks. A more recent diagnostic method utilizes isolated cosmids as probes to identify the chromosome 16 inversion by FISH. Although this is an improvement over karyotyping, problems with chromosome preparation from clinical samples still exist and all of the cytogenetic-based diagnoses are not sensitive to a small fraction of abnormal cells, i.e. are not helpful for monitoring for relapse.
It would therefore be desirable to identify the genes involved in the chromosome 16 arrangement. It would also be desirable to provide markers for the detection of chromosome 16 rearrangements. It would further be desirable to provide a method of diagnosing chromosome 16 rearrangements. It would also be desirable to provide a method of assessing treatment of acute myeloid leukemia patients. With the elucidation of the genes and breakpoints involved, conventional and genetic therapeutic approaches for the treatment of acute myeloid leukemia are also now feasible.